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class="yui-g" id="_modules-django-db-models-functions-base"> <h1>Source code for django.db.models.functions.base</h1><div class="highlight"><pre> <span></span><span class="sd">"""</span> <span class="sd">Classes that represent database functions.</span> <span class="sd">"""</span> <span class="kn">from</span> <span class="nn">django.db.models</span> <span class="k">import</span> <span class="n">Func</span><span class="p">,</span> <span class="n">Transform</span><span class="p">,</span> <span class="n">Value</span><span class="p">,</span> <span class="n">fields</span> <div class="viewcode-block" id="Cast"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Cast">[docs]</a><span class="k">class</span> <span class="nc">Cast</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Coerce an expression to a new field type.</span> <span class="sd"> """</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'CAST'</span> <span class="n">template</span> <span class="o">=</span> <span class="s1">'</span><span class="si">%(function)s</span><span class="s1">(</span><span class="si">%(expressions)s</span><span class="s1"> AS </span><span class="si">%(db_type)s</span><span class="s1">)'</span> <span class="n">mysql_types</span> <span class="o">=</span> <span class="p">{</span> <span class="n">fields</span><span class="o">.</span><span class="n">CharField</span><span class="p">:</span> <span class="s1">'char'</span><span class="p">,</span> <span class="n">fields</span><span class="o">.</span><span class="n">IntegerField</span><span class="p">:</span> <span class="s1">'signed integer'</span><span class="p">,</span> <span class="n">fields</span><span class="o">.</span><span class="n">FloatField</span><span class="p">:</span> <span class="s1">'signed'</span><span class="p">,</span> <span class="p">}</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">output_field</span><span class="p">):</span> <span class="nb">super</span><span class="p">(</span><span class="n">Cast</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">expression</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">output_field</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_sql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">extra_context</span><span class="p">):</span> <span class="k">if</span> <span class="s1">'db_type'</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">extra_context</span><span class="p">:</span> <span class="n">extra_context</span><span class="p">[</span><span class="s1">'db_type'</span><span class="p">]</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_output_field</span><span class="o">.</span><span class="n">db_type</span><span class="p">(</span><span class="n">connection</span><span class="p">)</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Cast</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">extra_context</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_mysql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="n">extra_context</span> <span class="o">=</span> <span class="p">{}</span> <span class="n">output_field_class</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_output_field</span><span class="p">)</span> <span class="k">if</span> <span class="n">output_field_class</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">mysql_types</span><span class="p">:</span> <span class="n">extra_context</span><span class="p">[</span><span class="s1">'db_type'</span><span class="p">]</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">mysql_types</span><span class="p">[</span><span class="n">output_field_class</span><span class="p">]</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">extra_context</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_postgresql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="c1"># CAST would be valid too, but the :: shortcut syntax is more readable.</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">template</span><span class="o">=</span><span class="s1">'</span><span class="si">%(expressions)s</span><span class="s1">::</span><span class="si">%(db_type)s</span><span class="s1">'</span><span class="p">)</span></div> <div class="viewcode-block" id="Coalesce"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Coalesce">[docs]</a><span class="k">class</span> <span class="nc">Coalesce</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Chooses, from left to right, the first non-null expression and returns it.</span> <span class="sd"> """</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'COALESCE'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="o"><</span> <span class="mi">2</span><span class="p">:</span> <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Coalesce must take at least two expressions'</span><span class="p">)</span> <span class="nb">super</span><span class="p">(</span><span class="n">Coalesce</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_oracle</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="c1"># we can't mix TextField (NCLOB) and CharField (NVARCHAR), so convert</span> <span class="c1"># all fields to NCLOB when we expect NCLOB</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">output_field</span><span class="o">.</span><span class="n">get_internal_type</span><span class="p">()</span> <span class="o">==</span> <span class="s1">'TextField'</span><span class="p">:</span> <span class="k">class</span> <span class="nc">ToNCLOB</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'TO_NCLOB'</span> <span class="n">expressions</span> <span class="o">=</span> <span class="p">[</span> <span class="n">ToNCLOB</span><span class="p">(</span><span class="n">expression</span><span class="p">)</span> <span class="k">for</span> <span class="n">expression</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_source_expressions</span><span class="p">()]</span> <span class="n">clone</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">copy</span><span class="p">()</span> <span class="n">clone</span><span class="o">.</span><span class="n">set_source_expressions</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Coalesce</span><span class="p">,</span> <span class="n">clone</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">)</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">)</span></div> <span class="k">class</span> <span class="nc">ConcatPair</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> A helper class that concatenates two arguments together. This is used</span> <span class="sd"> by `Concat` because not all backend databases support more than two</span> <span class="sd"> arguments.</span> <span class="sd"> """</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'CONCAT'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">left</span><span class="p">,</span> <span class="n">right</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="nb">super</span><span class="p">(</span><span class="n">ConcatPair</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">left</span><span class="p">,</span> <span class="n">right</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_sqlite</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="n">coalesced</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">coalesce</span><span class="p">()</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">ConcatPair</span><span class="p">,</span> <span class="n">coalesced</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">template</span><span class="o">=</span><span class="s1">'</span><span class="si">%(expressions)s</span><span class="s1">'</span><span class="p">,</span> <span class="n">arg_joiner</span><span class="o">=</span><span class="s1">' || '</span> <span class="p">)</span> <span class="k">def</span> <span class="nf">as_mysql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="c1"># Use CONCAT_WS with an empty separator so that NULLs are ignored.</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">ConcatPair</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">function</span><span class="o">=</span><span class="s1">'CONCAT_WS'</span><span class="p">,</span> <span class="n">template</span><span class="o">=</span><span class="s2">"</span><span class="si">%(function)s</span><span class="s2">('', </span><span class="si">%(expressions)s</span><span class="s2">)"</span> <span class="p">)</span> <span class="k">def</span> <span class="nf">coalesce</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="c1"># null on either side results in null for expression, wrap with coalesce</span> <span class="n">c</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">copy</span><span class="p">()</span> <span class="n">expressions</span> <span class="o">=</span> <span class="p">[</span> <span class="n">Coalesce</span><span class="p">(</span><span class="n">expression</span><span class="p">,</span> <span class="n">Value</span><span class="p">(</span><span class="s1">''</span><span class="p">))</span> <span class="k">for</span> <span class="n">expression</span> <span class="ow">in</span> <span class="n">c</span><span class="o">.</span><span class="n">get_source_expressions</span><span class="p">()</span> <span class="p">]</span> <span class="n">c</span><span class="o">.</span><span class="n">set_source_expressions</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="k">return</span> <span class="n">c</span> <div class="viewcode-block" id="Concat"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Concat">[docs]</a><span class="k">class</span> <span class="nc">Concat</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Concatenates text fields together. Backends that result in an entire</span> <span class="sd"> null expression when any arguments are null will wrap each argument in</span> <span class="sd"> coalesce functions to ensure we always get a non-null result.</span> <span class="sd"> """</span> <span class="n">function</span> <span class="o">=</span> <span class="kc">None</span> <span class="n">template</span> <span class="o">=</span> <span class="s2">"</span><span class="si">%(expressions)s</span><span class="s2">"</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="o"><</span> <span class="mi">2</span><span class="p">:</span> <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Concat must take at least two expressions'</span><span class="p">)</span> <span class="n">paired</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_paired</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="nb">super</span><span class="p">(</span><span class="n">Concat</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">paired</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">_paired</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">expressions</span><span class="p">):</span> <span class="c1"># wrap pairs of expressions in successive concat functions</span> <span class="c1"># exp = [a, b, c, d]</span> <span class="c1"># -> ConcatPair(a, ConcatPair(b, ConcatPair(c, d))))</span> <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="o">==</span> <span class="mi">2</span><span class="p">:</span> <span class="k">return</span> <span class="n">ConcatPair</span><span class="p">(</span><span class="o">*</span><span class="n">expressions</span><span class="p">)</span> <span class="k">return</span> <span class="n">ConcatPair</span><span class="p">(</span><span class="n">expressions</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span> <span class="bp">self</span><span class="o">.</span><span class="n">_paired</span><span class="p">(</span><span class="n">expressions</span><span class="p">[</span><span class="mi">1</span><span class="p">:]))</span></div> <div class="viewcode-block" id="Greatest"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Greatest">[docs]</a><span class="k">class</span> <span class="nc">Greatest</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Chooses the maximum expression and returns it.</span> <span class="sd"> If any expression is null the return value is database-specific:</span> <span class="sd"> On Postgres, the maximum not-null expression is returned.</span> <span class="sd"> On MySQL, Oracle, and SQLite, if any expression is null, null is returned.</span> <span class="sd"> """</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'GREATEST'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="o"><</span> <span class="mi">2</span><span class="p">:</span> <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Greatest must take at least two expressions'</span><span class="p">)</span> <span class="nb">super</span><span class="p">(</span><span class="n">Greatest</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_sqlite</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="sd">"""Use the MAX function on SQLite."""</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Greatest</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sqlite</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">function</span><span class="o">=</span><span class="s1">'MAX'</span><span class="p">)</span></div> <div class="viewcode-block" id="Least"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Least">[docs]</a><span class="k">class</span> <span class="nc">Least</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> Chooses the minimum expression and returns it.</span> <span class="sd"> If any expression is null the return value is database-specific:</span> <span class="sd"> On Postgres, the minimum not-null expression is returned.</span> <span class="sd"> On MySQL, Oracle, and SQLite, if any expression is null, null is returned.</span> <span class="sd"> """</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'LEAST'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">expressions</span><span class="p">)</span> <span class="o"><</span> <span class="mi">2</span><span class="p">:</span> <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Least must take at least two expressions'</span><span class="p">)</span> <span class="nb">super</span><span class="p">(</span><span class="n">Least</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_sqlite</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="sd">"""Use the MIN function on SQLite."""</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Least</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sqlite</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">function</span><span class="o">=</span><span class="s1">'MIN'</span><span class="p">)</span></div> <div class="viewcode-block" id="Length"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Length">[docs]</a><span class="k">class</span> <span class="nc">Length</span><span class="p">(</span><span class="n">Transform</span><span class="p">):</span> <span class="sd">"""Returns the number of characters in the expression"""</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'LENGTH'</span> <span class="n">lookup_name</span> <span class="o">=</span> <span class="s1">'length'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="n">output_field</span> <span class="o">=</span> <span class="n">extra</span><span class="o">.</span><span class="n">pop</span><span class="p">(</span><span class="s1">'output_field'</span><span class="p">,</span> <span class="n">fields</span><span class="o">.</span><span class="n">IntegerField</span><span class="p">())</span> <span class="nb">super</span><span class="p">(</span><span class="n">Length</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">expression</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="n">output_field</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_mysql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Length</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">function</span><span class="o">=</span><span class="s1">'CHAR_LENGTH'</span><span class="p">)</span></div> <div class="viewcode-block" id="Lower"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Lower">[docs]</a><span class="k">class</span> <span class="nc">Lower</span><span class="p">(</span><span class="n">Transform</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'LOWER'</span> <span class="n">lookup_name</span> <span class="o">=</span> <span class="s1">'lower'</span></div> <div class="viewcode-block" id="Now"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Now">[docs]</a><span class="k">class</span> <span class="nc">Now</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="n">template</span> <span class="o">=</span> <span class="s1">'CURRENT_TIMESTAMP'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">output_field</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="k">if</span> <span class="n">output_field</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span> <span class="n">output_field</span> <span class="o">=</span> <span class="n">fields</span><span class="o">.</span><span class="n">DateTimeField</span><span class="p">()</span> <span class="nb">super</span><span class="p">(</span><span class="n">Now</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">output_field</span><span class="o">=</span><span class="n">output_field</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_postgresql</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="c1"># Postgres' CURRENT_TIMESTAMP means "the time at the start of the</span> <span class="c1"># transaction". We use STATEMENT_TIMESTAMP to be cross-compatible with</span> <span class="c1"># other databases.</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">template</span><span class="o">=</span><span class="s1">'STATEMENT_TIMESTAMP()'</span><span class="p">)</span></div> <div class="viewcode-block" id="Substr"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Substr">[docs]</a><span class="k">class</span> <span class="nc">Substr</span><span class="p">(</span><span class="n">Func</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'SUBSTRING'</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">pos</span><span class="p">,</span> <span class="n">length</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">):</span> <span class="sd">"""</span> <span class="sd"> expression: the name of a field, or an expression returning a string</span> <span class="sd"> pos: an integer > 0, or an expression returning an integer</span> <span class="sd"> length: an optional number of characters to return</span> <span class="sd"> """</span> <span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">pos</span><span class="p">,</span> <span class="s1">'resolve_expression'</span><span class="p">):</span> <span class="k">if</span> <span class="n">pos</span> <span class="o"><</span> <span class="mi">1</span><span class="p">:</span> <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s2">"'pos' must be greater than 0"</span><span class="p">)</span> <span class="n">pos</span> <span class="o">=</span> <span class="n">Value</span><span class="p">(</span><span class="n">pos</span><span class="p">)</span> <span class="n">expressions</span> <span class="o">=</span> <span class="p">[</span><span class="n">expression</span><span class="p">,</span> <span class="n">pos</span><span class="p">]</span> <span class="k">if</span> <span class="n">length</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span> <span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">length</span><span class="p">,</span> <span class="s1">'resolve_expression'</span><span class="p">):</span> <span class="n">length</span> <span class="o">=</span> <span class="n">Value</span><span class="p">(</span><span class="n">length</span><span class="p">)</span> <span class="n">expressions</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">length</span><span class="p">)</span> <span class="nb">super</span><span class="p">(</span><span class="n">Substr</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="o">*</span><span class="n">expressions</span><span class="p">,</span> <span class="o">**</span><span class="n">extra</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_sqlite</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Substr</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">function</span><span class="o">=</span><span class="s1">'SUBSTR'</span><span class="p">)</span> <span class="k">def</span> <span class="nf">as_oracle</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">):</span> <span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">Substr</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">as_sql</span><span class="p">(</span><span class="n">compiler</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="n">function</span><span class="o">=</span><span class="s1">'SUBSTR'</span><span class="p">)</span></div> <div class="viewcode-block" id="Upper"><a class="viewcode-back" href="../../../../../ref/models/database-functions.html#django.db.models.functions.Upper">[docs]</a><span class="k">class</span> <span class="nc">Upper</span><span class="p">(</span><span class="n">Transform</span><span class="p">):</span> <span class="n">function</span> <span class="o">=</span> <span class="s1">'UPPER'</span> <span class="n">lookup_name</span> <span class="o">=</span> <span class="s1">'upper'</span></div> </pre></div> </div> </div> </div> <div class="yui-b" id="sidebar"> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <div class="searchformwrapper"> <form class="search" action="../../../../../search.html" method="get"> <input type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <h3>Last update:</h3> <p class="topless">Feb 11, 2019</p> </div> </div> <div id="ft"> <div class="nav"> <a href="../../../../index.html" title="Module code" accesskey="U">up</a></div> </div> </div> <div class="clearer"></div> </div> </body> </html>